1. Field of the Invention
This invention relates to a laminated evaporator, and more particularly it relates to a heat exchanger-type laminated evaporator used in an air conditioner of an automobile or like vehicle.
2. Description of the Prior Art
A heat exchange-type evaporator to be used in an air conditioner of a vehicle such as an automobile, according to the prior art, for example, British Pat. Nos. 1,304,691 and 1,051,601, is made of integral metal plates having deep recessed parts at both ends in communication with each other by shallow recessed grooves. Two such plates are laminated with the recesses facing each other to make a single flat pipe communicating with compartments formed by the deep recesses at each of the upper and lower ends. A plurality of such single pipes are arranged in side-by-side relation. Several such laminates are stacked with the outer surfaces of each recess juxtaposed to the outer surface of a recess of an adjacent laminate and all the juxtaposed surfaces are punched to communicate with each other, thereby forming the compartments into tanks at the upper and lower ends of the single pipe with the flat pipes of one laminate opposed to and spaced from the flat pipes of an adjacent laminate. Corrugated fins are held between the opposed flat pipes to form a core part therein. Outlet and inlet pipes are connected, respectively, to the upper and lower tanks. In such an evaporator, refrigerant which has been fed from the inlet pipe to the lower tank is passed through the flat pipes into the upper tank and is evaporated therein by heat exchange with air fed through the corrugated fins and the air passing through the fins is cooled by the latent heat of vaporization of the refrigerant.
However, in such a laminated type evaporator, when a large volume of refrigerant is fed into the lower tank, a distribution of the refrigerant into each of the flat pipes is relatively uniform and, to the contrary, when a rate of flow of the refrigerant is decreased, the distribution of the refrigerant into each of the flat pipes becomes non-uniform and the performance of the evaporator is decreased. For example, in such an evaporator, the distribution of the refrigerant from a position A nearest to the inlet pipe to a position B farther therefrom is sufficiently uniform at a high rate of inflow, as shown in curve a of FIG. 1, but at a low rate of flow, it is not. Thus, at a low rate of flow, there is a larger difference, .DELTA.H.sub.1, in the distribution between the position A and the position B, as shown in curve b, which causes a deterioration in the performance.
In order to eliminate such defects, in accordance with U.S. Pat. No. 3,976,128 of C. N. Patel et al., a tube having orifices punched at a certain angle against the air inlet side of the evaporator is inserted into the lower tank, and the tube is connected with the inlet pipe. However, it is difficult to provide a correct installation of the tube having such structure as described above. When a rate of flow of refrigerant is low, even if the tube has such structure as described above, a good distribution of the refrigerant is not adequately obtained.